package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.SeckillVoucher;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.SimpleRedisLock;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.servlet.View;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.time.LocalDateTime;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        //设置脚本位置 ClassPathResource会在根路径下找
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        //设置返回值类型
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    //线程池 单个线程即可
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    //项目启动后执行 异步任务 要一直等着消息
    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    //异步任务 redis的Stream消息队列
    private class VoucherOrderHandler implements Runnable{
        String queueName = "stream.orders";
        @Override
        public void run() {
            while (true){
                try {
                    //1.获取消息队列中的订单信息 XREADGROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS streams.order >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    //2.判断消息获取是否成功
                    if (list==null || list.isEmpty()) {
                        //2.1 如果获取失败 结束或继续下一次循环
                        continue;
                    }
                    //3 解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    //3 获取成功 可用下单
                    handleVoucherOrder(voucherOrder);
                    //4 做ACK确认 sack stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());
                } catch (Exception e) {
                    //5处理消息时出现异常 没有被ack处理 进入pending-list
                    handlePendingList();
                    log.error("处理订单异常：",e);
                }
            }
        }

        private void handlePendingList() {
            while (true){
                try {
                    //1.获取Pending-list中的订单信息 XREADGROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS stream.orders 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    //2.判断消息获取是否成功
                    if (list==null || list.isEmpty()) {
                        //2.1 如果获取失败 说明pending-list中没有异常消息 结束循环
                        break;
                    }
                    //3 解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    //3 获取成功 可用下单
                    handleVoucherOrder(voucherOrder);
                    //4 做ACK确认 sack stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());
                } catch (Exception e) {
                    //这里异常不用递归，会直接继续下一次循环
                    log.error("处理pending-list异常：",e);
                    //担心循环太过频繁，可以休眠一段时间
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        ex.printStackTrace();
                    }
                }
            }
        }

    }




    /*//阻塞队列 线程异步调用
    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
    //异步任务
    private class VoucherOrderHandler implements Runnable{
        @Override
        public void run() {
            while (true){
                try {
                    //1.获取阻塞队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常：",e);
                }
            }
        }
    }*/

    //创建订单
    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getUserId();
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //获取锁 tryLock() 无参数默认等待时间-1 默认超时时间30s
        boolean isLock = lock.tryLock();
        //判断是否获取锁成功
        if (!isLock) {
            //获取锁失败 异步处理 不用给前端返回说明  而且理论上不用加锁  兜底
            log.error("不允许重复下单");
        }
        //获取锁
        try {
            //子线程 拿不到代理对象 在父线程定义
            proxy.createVoucherOrder(voucherOrder);
        } catch (IllegalStateException e) {
            throw new RuntimeException(e);
        } finally {
            //释放锁
            lock.unlock();
        }
    }

    private IVoucherOrderService proxy;

    /**
     * 使用Redis的Stream消息队列实现秒杀券下单
     */
    @Override
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();
        //获取订单id
        long orderId = redisIdWorker.nextId("order");
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString(),
                String.valueOf(orderId)
        );
        //2.判断结果是否为0
        int r = result.intValue();
        if (r != 0) {
            //2.1 不为0，没有下单资格
            return Result.fail(r == 1?"库存不足！":"不能重复下单！");
        }
        //2.2 为0 可以下单，将下单信息[优惠券id、订单id]封装保存到阻塞队列中

        //获取代理对象 ， 以便子线程调用
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        //3 返回订单id
        return Result.ok(orderId);
    }

    ///**
    // * 秒杀券下单功能【基于redis的lua脚本实现秒杀优化】
    // */
    //@Override
    //public Result seckillVoucher(Long voucherId) {
    //    //获取用户
    //    Long userId = UserHolder.getUser().getId();
    //    //1.执行lua脚本
    //    Long result = stringRedisTemplate.execute(
    //            SECKILL_SCRIPT,
    //            Collections.emptyList(),
    //            voucherId.toString(), userId.toString()
    //    );
    //    //2.判断结果是否为0
    //    int r = result.intValue();
    //    if (r != 0) {
    //        //2.1 不为0，没有下单资格
    //        return Result.fail(r == 1?"库存不足！":"不能重复下单！");
    //    }
    //    //2.2 为0 可以下单，将下单信息[优惠券id、订单id]封装保存到阻塞队列中
    //    long orderId = redisIdWorker.nextId("order");
    //    //TODO 保存阻塞队列
    //    VoucherOrder voucherOrder = new VoucherOrder();
    //    //2.3订单id
    //    voucherOrder.setId(orderId);
    //    //2.4用户id
    //    voucherOrder.setUserId(userId);
    //    //2.5代金券id
    //    voucherOrder.setVoucherId(voucherId);
    //    //2.6放入阻塞队列
    //    orderTasks.add(voucherOrder);
    //
    //    //获取代理对象 ， 以便子线程调用
    //    proxy = (IVoucherOrderService) AopContext.currentProxy();
    //
    //    //3 返回订单id
    //    return Result.ok(orderId);
    //}


    ///**
    // * 秒杀券下单功能
    // */
    //@Override
    //public Result seckillVoucher(Long voucherId) {
    //    //1.查询优惠券信息
    //    SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
    //    //2.判断秒杀是否开始
    //    if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
    //        //尚未开始
    //        return Result.fail("秒杀尚未开始！");
    //    }
    //    //3.判断秒杀是否结束
    //    if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
    //        //已经结束
    //        return Result.fail("秒杀已经结束！");
    //    }
    //    //4.判断库存是否充足
    //    if (voucher.getStock() < 1) {
    //        //库存不足
    //        return Result.fail("库存不足！");
    //    }
    //
    //    Long userId = UserHolder.getUser().getId();
    //
    //    //创建锁对象
    //    //SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
    //    RLock lock = redissonClient.getLock("lock:order:" + userId);
    //
    //    //获取锁 tryLock() 无参数默认等待时间-1 默认超时时间30s
    //    boolean isLock = lock.tryLock();
    //    //判断是否获取锁成功
    //    if (!isLock) {
    //        //获取锁失败 错误或重试
    //        return Result.fail("不允许重复下单！");
    //    }
    //    //获取锁失败
    //    try {
    //        IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
    //        return proxy.createVoucherOrder(voucherId);
    //    } catch (IllegalStateException e) {
    //        throw new RuntimeException(e);
    //    } finally {
    //        //释放锁
    //        lock.unlock();
    //    }
    //
    //
    //    //synchronized (userId.toString().intern()) {
    //    //    IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
    //    //    return proxy.createVoucherOrder(voucherId);
    //    //}
    //}

    /**
     * 异步线程创建订单方法
     */
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder){
        //6 一人一单
        Long userId = voucherOrder.getUserId();

        //6.1查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        //6.2判断是否存在
        if (count>0) {
            //用户购买过该券
            log.error("用户已经购买过一次！");
            return;
        }
        //有库存
        //5.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1") // set stock = stock - 1
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock",0) //where id = ? and stock > 0
                .update();
        if (!success) {
            //扣减失败
            log.error("库存不足");
            return;
        }
        //创建订单
        save(voucherOrder);
    }


    /**
     * 原始创建订单方法
     */
    @Transactional
    public Result createVoucherOrder(Long voucherId){
        //6 一人一单
        Long userId = UserHolder.getUser().getId();

        //6.1查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        //6.2判断是否存在
        if (count>0) {
            //用户购买过该券
            return Result.fail("用户已经购买过一次！");
        }

        //有库存
        //5.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1") // set stock = stock - 1
                .eq("voucher_id", voucherId).gt("stock",0) //where id = ? and stock > 0
                .update();
        if (!success) {
            //扣减失败
            return Result.fail("库存不足！");
        }

        //6.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        //6.1订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //6.2用户id
        //Long userId = UserHolder.getUser().getId();
        voucherOrder.setUserId(userId);
        //6.3代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        //7.返回订单ID
        return Result.ok(orderId);

    }

}
